Comey told Justice Department officials that he planned to tell lawmakers about newly uncovered emails he said were "pertinent" to his agency's investigation into Hillary Clinton's private server, according to a report by the Washington Post.
Those officials warned Comey that his announcement was a break with policy and tradition.
"Director Comey understood our position. He heard it from Justice leadership," an unnamed Justice Department official told the Post.
The official said that Comey then made an "independent decision" to notify Congress.
"He is operating independently of the Justice Department," the official told the Post. "And he knows it."